Multiple Access Communications are previously known. In e.g. mobile communications systems such as GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System) users or user equipment are allocated communications resources depending on demand and availability.
Multiple Access Communications usually relies upon multiplexing technologies for dividing or splitting a channel resource into components of more limited capacity. Examples of such technologies are FDM (Frequency Divisions Multiplex), TDM (Time Division Multiplex) and CDM (Code Division Multiplex) with associated multiple access technologies FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access) respectively. According to prior art, users are multiplexed by dividing an entire bandwidth resource into channels or channel resources characterized by orthogonality in frequency, time and code domain, respectively. Also known in prior art are multiplexing systems combining two or more of FDM, TDM and CDM thereby achieving channels or channel resources characterized by orthogonality in two or more domains, e.g. time and frequency domain.
Prior art recognizes both circuit switched communications and packet switched communications. In circuit switched communications, communications resources are allocated, even if they temporarily or due to channel conditions could be released, for an entire communications session, e.g. an entire phone call or an entire telephone modem data connection of one or more data transfers. In packet switched communications, communications resources are allocated according to communications requirements for distribution of packets not necessarily forming an entire communications session, e.g. a fraction of a digitized spoken sentence or a fraction of a data file.
Varying channel characteristics, e.g. interference, of prior art systems are compensated for by particularly transmission power control and channel equalization. If received signal strength so mandates, channel handover may be initiated.
There are also known prior art systems for exploring channel dynamics, such as MIMO (Multiple Input Multiple Output) MISO (Multiple Input Single Output) and SIMO (Single Input Multiple Output). In such systems, channel state information is typically fed back from receiver to transmitter.
From prior art channel probing is also previously known. When an HF (High Frequency) channel is probed for optimum frequency of operation or a radio communications channel is probed for appropriate transmission power level, it is an example of channel probing.
U.S. Patent Application US2002/0183086 discloses channel probing in a CDMA system. A mobile station increases transmission power level until a base station acknowledgement is received. The power level at which an acknowledgement is received is stored and forms a basis for the power level at which a second probe is initiated, thereby reducing time to acknowledgement of second probe.
U.S. Pat. No. 6,546,045 reveals channel probing in a communications system for selection of one out of two available modulation schemes. A probe signal is transmitted for estimation of channel multipath and Doppler characteristics. Adaptive modems measure the communication channel's Doppler and multipath characteristics. Upon the occurrence of predetermined criteria, the channel scattering function estimate may be updated and a new modulation scheme may be selected to continue transmission.
U.S. Pat. No. 6,400,783 reveals channel probing in a communications system for channel estimation and channel equalization.
G. Foschini, ‘Layered Space-Time Architecture for Wireless Communication in a Fading Environment When Using Multi-Element Antennas,’ Bell Labs Technical Journal, Autumn 1996, addresses digital communication in a Rayleigh fading environment and analyzes (nT,nR)-systems with nT transmit antenna elements and nR receive antenna elements. The architecture has also been marketed as BLAST (‘Bell Layered Space-Time Architecture’).
C. Schlegel, Z Bagley, ‘Efficient Processing for High-Capacity MIMO Channels’ JSAC, MIMO Systems Special Issue, Apr. 23, 2002, and C. Schlegel, Zachary Bagley, ‘MIMO Channels and Space-Time Coding, WOC 2002, July 2002, presents fundamental results and methods for capacity for MIMO, discusses ray-tracing channel models and realizable capacity, discusses error performance measures and decoding algorithms for space-time coding and the addition of error control coding to space-time systems.
Siavash M. Alamouti, ‘A Simple Transmit Diversity Technique for Wireless Communications,’ IEEE Journal on Sel. Areas in Communications, October 1998, discloses a two-branch transmit diversity scheme. Diversity gain in Rayleigh fading is demonstrated with two transmit antennas and with coding over two symbol intervals.
None of the cited documents above discloses channel characteristic dependent channel allocation, grouping users of different channel characteristics into disjoint groups. None of the cited documents discloses users of different groups being allocated non-interfering channels or channels of more limited interference than the mutual interference between channels within a group. Example channels are orthogonal channels, which can be achieved by means of, e.g., frequency orthogonality, non-overlapping transmission time intervals or orthogonal codes.